Strange deforming when using bones
I don't see any strange deformation there. You weightpainted the same vertices with full weight to multiple Bones, so the vertice position is interpolated between all the Bone locations which have weight assigned to them.

You have to weight the vertices only to one Bone, and maybe use some low weight blending between them.

The Updates Issue has most likely the same root: the bad vertice is influenced by another bone - doublecheck that all other bones have 0 weight on it and the correct Bone has full weight.